Jeffrey H. Gillman1 and David C. Zlesak2 Department of Horticultural Science, University of Minnesota, St. Paul, MN 55108 Received for Publication 25 Aug. 1999. Accepted for Publication 1 Dec. 1999. Minnesota Experiment Station # 981210039. The authors would like to thank Erica Davis and Robert Ford for technical assistance. The cost of publishing this paper […]

Cymbidium Light and Temperature: 2,000-4,000 foot-candles. Cymbidium orchids may be grown outdoors in areas where heavy frost does not occur. They need filtered sunlight or full sun for half a day and good air movement. Foliage will be slightly yellow green, not dark green. Cymbidiums withstand a great deal of heat and cold. Night temperatures […]

Sodium is involved in osmotic (water movement) and ionic balance and is required for some plants. Cobalt is required for nitrogen fixation in legumes and in root nodules of nonlegumes because it is a component of enzymes essential for nitrogen fixation. Deficient levels could result in nitrogen deficiency symptoms. Silicon is found as a component […]

The following is a brief summary of the role of essential and beneficial mineral nutrients crucial to plant growth. If any one of the essential elements is eliminated from a plantís nutrition, it will display abnormalities of growth, symptoms of deficiency, and may not reproduce normally. Essential Micronutrients Iron is a component of many structural […]

The following is a brief summary of the role of essential and beneficial mineral nutrients crucial to plant growth. If any one of the essential elements is eliminated from a plantís nutrition, it will display abnormalities of growth, symptoms of deficiency, and may not reproduce normally. Essential Macronutrients: Nitrogen is a major component of proteins, […]

Enzymes are proteins which are involved in increasing the rate and efficiency of biochemical reactions. Most enzymes require metal ions for activation and function. Without proper enzyme function, growth would cease in an organism. Most of the essential mineral elements affect enzymes in multiple ways.

The term pH refers to the alkalinity or acidity of a growing medium water solution. This solution consists of mineral elements dissolved in ionic form in water. The reaction of this solution whether it is acid, neutral or alkaline will have a marked effect on the availability of mineral elements to plant roots. When there […]

The Cation Exchange Capacity refers to the ability of the growing medium to hold exchangeable mineral elements within its structure. These cations include ammonium (nitrogen), potassium, calcium, magnesium, iron, manganese, zinc and copper. Peat moss and mixes containing bark, sawdust, and other organic materials all have some level of cation exchange capacity.

The use of soil for greenhouse production before the 1960s was common. Today a few growers still use soil in their mixes. The bulk of production is in soilless mixes. Soilless mixes must provide support, aeration, nutrient and moisture retention just as soils do, but the addition of fertilizers or nutrients are different. Many soilless […]